Plug for well flow conductors



May 28, 1963 i M w y f G. W. EVANS ETAL PLUG FOR WELL FLOW CONDUCTORS Filed Nov. 9, 1960 INVENTORS Jo h n R. L0 n d G qrge W. Evans BY 1 2 ATTORNEYS United States Patent 3,091,294 PLUG FOR WELL FLOW CONDUCTORS George W. Evans and John R. Land, Duncan, Okla assignors to Halliburton Company, Duncan, Okla a corporation of Delaware Filed Nov. 9, 1960, Ser. No. 68,271 11 Claims. (Cl. 166-193) This invention relates to well tools and more particularly to a plug for closing the flow passage of a well How conductor, such as well tubing or well casing.

In various operations of a well, such as well cementing, it is desirable to close the flow passage of a fi ow conductor, such as tubing, at a desired position in the well tubing by a plug which may be pumped downwardly through the fiow passage to the desired position at which a stop means for arresting downward movement of the plug through the tubing is located. It is often desirable that such plug close the flow passage against fluid new in either direction therethrough.

Accordingly, it is one object of this invention to pro: vide a new and improved plug for closing the flow passage of a well conductor such as well tubing. 7 7 V t to Another object is to provide a plug which'rnay be pumped downwardly through the flow passage of the flow conductor to a predetermined position inihe well tubing where its further downward movement is arrested by a stop member or seat positioned at the coupling recess between adjacent sections of the tubing, V

Still another object is to provide a plug which has means engageable with the stop or seat insert in the tubing to prevent movement of the plug from the predetermined position in the tubing once it has located at such predetermined position. a V 7 V V A further object is to provide a plug engageable with a stop or seat insert positioned at the coupling recesst between two adjacent sections of a tubing and: having sealing means for engaging the internal wall surfaces of both sections of the tubing to close the tubing above and below the stop or seat insert whereby such stop or seat insert need not be pro ided with any means for sealing with the tubing 7 A still further object is to provide a plug for a well conductor having a mandrel provided with a stop shoulder engageable with an upwardly facing shoulder of a stop or seat insert in the well conductor to arrest downward movement of the plug through the well conductor, a latch means for engaging a downwardly; facing shoulder of the seat insert to limit upward movement of'the mandrel from the seat insert and seal means mounted on opposite ends of the mandrel for engaging the internal wall surfaces of the well conductor above and below the seat insert.

Another object is to provide a plug of the type described having latch means which function to prevent movement of the plug from the stop or seat insert regardless of which end of the plug is in lower position in 1 the flow conductor, and regardless of which endtof'the plug is subjected to pressure or to a pressure differential. 60

Still another object is to provide a plug wherein the mandrel is provided with a pair of spaced latch or snap rings, one engaging the stop or seat insert to prevent rupward movement of the plug from the insert when one 3,091,294 7 Patented May 2 8, 1963 A further Qhi ect'i s to provide a stop or seat insert and plugr forgajtfiowconductor wherein the stop or seat insert may be'molunted ata collar recess of the flow conductor between adjacent ends of adjacent tubing sections without regard'to twillich end of the insert is in upper or lower position iii theitub'rng and a plug which may be introduced: intothe tubing Without regard to which end of the plug is in upper or lower position in the tubing; and further provided with seal means which close off flow of fluidsthrcugh the bore of the flow conductor in either dirnQ iOZlt Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawiugseth'ereof, wherein:

FIGURE Lisa'fragmentary vertical sectional view 0 t dwell tubing provided with a stop or seat insert at a 'and the. plug.

Referring nowparticularly to FIGURES 1, 2 and 3 of the drawing, the plug embodying the invention is employed tosclose the bore or flow passage of a tubing string T. annular stop or seat insert 12 is mounted in the tubing stringlat the, coupling or collar recess 13 formed sbetwenithe upper and lower ends of the tubing SQQflflflQflW-filldiii rigidly connected together by a collar 16; whichjreoess may be any desired one of the many recesses uniformed in a string of tubing. The seat insert 12 has a reduced upper portion which provides an up Wardly facing external annular shoulder .17 engageable withsthe lower end '18 of the upper tubing section 14 to limit upward movement of the insert in the tubing, downwardtrrovement of the insert being prevented by the ent gagem'enl of t'he lower annular end 19 of the insert with the upper 'end' 20 of the lower tubing section 15. The reduced upper portion 22 of the seat insert telescopes into; the loweiend of the upper tubing section, and has an internal downwardly and inwardly beveled upper stop shoulder {or seat-24. The bore of the annular seat insert is enlaigedat its lower portion to provide a downwardly ofirilng'hnnular recess 25 with an annular downwardly facing lock shoulder 26 defining the upper end of the st s t The 'plug' 1B- includes a mandrel 30 having its upper reduced threaded end portion 31 received in the threaded bore 32 of a core 33 of an upper seal member assembly 351;. The seal assembly includes a resilient bulbous seal element 35, which may be molded about the core 33,

end of the plug is first introduce-d downwardly into thin tubing and the other latch ring being cn-gagjible'swith" the seat insert to prevent upward removal of the plug from the seat insert when the other end of the plug is first introduced downwardly to the tubing, whereby it is' assured that the plug will be latched at the stop or seat insert regardless of which position the plug is inserted in the tubing.

7 having an annular inwardly extending lip 37 covering the larger endoi the core and disposed between the annular upwardly facing shoulder 77-32 of the mandrel and the downwardly'facing shoulder 40 of the core to help pre- "vent'sepa'ratiibu of the seal element 35 from the core.

The mairimniiidiazrieter of the bulbous seal element in its undeformed condition is greater than the internal diameter oi the tubing, so that the resilient sealing element is compressed and deformed when inserted into the tubing by its engagement with the internal surfaces of the tubing.

The lower reduced threaded end portion 42 of the mandrel 30 is received in the threaded bore 43 of the core 44 embedded in the seal element 46 of the lower seal assembly 47, corresponding otherwise in all respects to the upper seal assembly 34. The seal element 46 is also formed of a resilient substance and has an internal annular lip 48 disposed between the downwardly facing shoulder 49 of the external annular flange 50 of the mandrel and the upwardly facing shoulder 51 of the core 44 to help prevent separation of the plug from the core.

A latch sleeve 60 is disposed about and confined on the mandrel 30, its downward movement on the mandrel being limited by the engagement of its lower end with the upwardly facing annular shoulder 61 of the flange 50 of the mandrel and its upward movement on the mandrel being limited by the engagement of its upper end with the lower end of the upper seal assembly 34. The upper end of the latch sleeve has an external annular flange 63 which provides a downwardly and inwardly beveled stop shoulder 64 engageable with the upwardly facing stop shoulder 24 of the valve insert to arrest downward movement of the mandrel through the valve insert. The latch sleeve is also formed with a downwardly opening external annular recess 66 in which is disposed a split resilient latch or snap ring 67 and a split spring 69 which biases the latch ring outwardly of the recess 66 of the sleeve. The latch ring has a downwardly facing beveled shoulder 70 which cams the latch ring inwardly into the recess 66 of the sleeve upon its engagement with such upwardly facing obstructions as the shoulder 24 of the seat insert during downward movement of the plug through the tubing string. The upper annular surface of the latch ring is substantially planar and provides a lock shoulder 68 on said ring which is adapted to engage the downwardly facing lock shoulder 26 of the stop or seat insert 12 to lock the plug against upward movement in the tubing when the latch ring is disposed in the recess 25, as will be hereafter more fully explained.

The upper seal element may be provided with some identifying characteristic such as the external annular flange 72 to distinguish it from the lower seal element so that the upper and lower ends of the plug may be readily distinguished.

In use, when it is desired to close the flow passage of the tubing string T at the point where the stop or seat insert 12 is located, the plug is inserted into the upper end of the tubing T with the lower seal assembly 47 disposed below the upper seal assembly 34. The bulbous seal elements 35 and 46 are compressed and deformed as they are inserted into the tubing string since their maximum external diameter, when in an undeformed condition, is greater than the internal diameter of the tubing string. As a result, the sealing elements engage the internal wall surfaces of the tubing string in sealing relation thereto. Fluid under pressure is then pumped into the tubing string above the plug to force the plug downwardly through the tubing.

As the plug 10 reaches the stop or seat insert 12, the seal element 46 first engages the downwardly and inwardly beveled shoulder 24, is further compressed and deformed by its engagement with this shoulder, and passes downwardly through the seat insert to expand again below the seat insertion into sealing engagement with the internal surfaces of the lower tubing section 15. Downward movement of the plug continues due to the fluid pressure above the plug and causes the snap latch ring to move inwardly into the recess 66 of the latch sleeve of the plug as the beveled shoulder 70 of the snap ring engages the beveled stop shoulder 24 of the seat insert and thus permits further downward movement of the plug through the seat insert. Downward movement of the plug is arrested when the downwardly facing stop shoulder 64 of the sleeve engages the beveled upper stop shoulder 24 of the seat insert. The bulbous seal element 35 of the upper seal assembly 34 of the plug now sealingly engages the internal surfaces of the upper tubing section above the seat insert and the seal element 46 of the lower seal assembly of the plug 10 now sealingly engages the internal surfaces of the lower tubing section.

The latch ring 67 is also in registry with and moves outwardly into the latch recess 25 of the seat insert when such ring is moved downwardly below the downwardly facing lock shoulder 26, so that any upward movement of the plug is arrested by the engagement of the upper lock surface 68 of the snap ring with the downwardly facing annular lock shoulder 26 of the seat insert. As a result, the plug 10 is latched in position in the tubing against longitudinal movement in either direction, downward movement being prevented by the engagement of the shoulder 64 of the sleeve of the plug and the shoulder 24 of the seat insert, and upward movement being arrested by the engagement of the upper lock surface of the snap latch ring with the downwardly facing lock shoulder 26 of the seat insert. The longitudinal dimension of the latch ring is smaller than that of the recess 25 of the seat insert in order to insure that the latch snap ring will be located below the latch shoulder 26 of the seat insert even if some foreign matter, such as sand or trash, is caught between the shoulder 64 of the sleeve and the shoulder 24 of the seat insert.

The seal elements 35 and 46 deform as greater fluid pressure is applied thereto, so that the seal between the plug and the tubing sections above and below the seat insert is rendered more effective as the fluid pressures increase in the tubing above or below the plug.

Since the plug has seal elements which sealingly engage the adjacent upper and lower tubing sections 14 and 15 on opposite side of the seat insert, the bulbous seal element 35 of the upper seal assembly deforms and prevents downward flow of fluid past the plug, and the bulbous seal element 46 of the lower sealing assembly deforms to prevent upward flow of fluid past the plug. As a result, no sealing means are necessary between the stop or seat insert and the tubing sections or between the insert and the plug.

It will now be seen that a new and improved plug for closing the flow passage of a flow conductor, such as the tubing T has been illustrated and described, which plug may be moved to a predetermined location in the flow passage of the tubing string to be latched thereat against longitudinal movement in either direction from such predetermined position.

It will also be seen that the plug includes a downwardly facing stop shoulder or stop means 64 for engaging a stop or seat insert provided at the desired location in the tubing string to stop downward movement of the plug at such desired location, and has latch means, such as the snap ring 67, for engaging a downwardly facing lock or latch shoulder 26 in the bore of the seat insert to prevent upward movement of the plug from the desired position.

It will further be seen that the plug is provided with seal means, for sealing with the internal surfaces of the flow conductor above and below the seat insert, which are deformable into increased sealing engagement by increased fluid pressures either above or below, or both, whereby the plug seals against flow of fluids in either direction past the plug.

In FIGURE 4 is illustrated a modified form of the plug embodying the invention and a modified form of the seat insert, which are longitudinally symmetrical so that the insert may be mounted in the tubing, and the plug may be inserted into the tubing without regard for whichever ends of the elements are in upper or lower positions. The modified plug includes an elongate mandrel 101 whose opposite ends are threadedly received in the threaded bores 102 of the cores 103 of the upper and lower seal assemblies 105. and 106, respectively. The upper and lower seal assemblies are identical in construction and have resilient bulbou sfseal' elements 108 in which the cores are embedded. Each or the inwardly extending flanges or lips @109 of the bulbous seal elements extends inwardly between the shoulder 112 of its core and the outer annular shoulder -11?: of an adjacent retainer ring 111 confined on the mandrel 101 between said seal elements and a central sleeve 110. The sleeve 110 is provided adjacent its opposite ends with the' annular recesses 114 in which latch or'snap lock rings 116 are resiliently mounted and biased outwardly by the. split springs 117. The latch or lock rings extend outwardly of the recesses 114 for a purpose 'to be hereinafter more fully explained; The latch rings, first described, which are identical in constructionwith the snap ring 67, have annular cam shoulders 12 and opposed inwardly facing lock shoulders 118 correspond; ing to the lock shoulder 68 of the form first described.

The sleeve 110 is provided intermediate its with an annular external flange 121 which provides the out" wardly convergent oppositely facing stop shoulders 122.

The stop or seat insert 125 has an external flange 126 receivable in the recess fortfie'tfit the collar 16 of the tubing string T. The upwardly 'facingannular shoulder 127 of the flange engages the [secrets '18 of the upper tubing section 14 and its down d1 facing annular shoulder 129 engages the upper ofth'e' lower tubing section 15. The opposite externally reduced ends of the insert are telescoped into the upper and lower tubing sections and have opposed inwardly convergent beveled stop shoulders 130 and 131 The seat insert is provided with an internal annular latchor locking recess 133 defined by longitudinally spaced upwardly and downwardly facing lock shoulders 134 and 135, respectively. V V

In use, when it is desired to close the iiow passage of the tubing at the point in the tubing at which'the seat insert 125 is located, the plug 100 is introduced into the upper end of the tubing and forced downwardly by fluid pressure introduced at the upper end ofthe' tubing'thereabove. The resilient bulbous seal elements'ltts of the seal assemblies 105 and 106 are of greater diameter, when in normal nondcformed condition, than tlte internal diameter of the tubing so that the seal elements are compressed and deformed, when inserted into the tubing, into sealing engagement with the internal surfaces of the tubing string. When the seal element 108 of whichever seal assembly 105 or 106 is in the lower position in the tubing encounters the inwardly beveled stop shoulder 130 at the upper end of the seat insert 125; the seal element is compressed to pass through the insert to the po'sition illustrated in FIGURE -4, where it is disposed below the seat insert in sealing contact with the internal surface of the lower tubing section 15. During Such downward movement of the plug through the seat insert, the cam in either direction and thus latch the plug to the stop or seat insert. 'The sealing elements 108 also sealingly engage the internal surfaces of the two tubing sections on opposite sig'esofthe seat insert to prevent flow of fluid througlritlie' tubing string in either direction, in the same manner as the sealing assemblies of the form first described'i; 4

It'wsll'be apparent that the plug 100 may be used with a tubing string having the seat insert 12 as well as with a tubing string having the seat insert 125. The seat insert 1 being'iongitudinally symmetrical, may be positioned with either end upward whereas the seat insert 12 must be positioned with the lock shoulder 26 thereof in a'downwardly facing position. It will be apparent that thislatter construction prevents a careless operator from positioning the seat insert 12 with the shoulder 24 facing downwafiiyfandthat by use thereof the plugs 10 or 100 may be properly positioned and latched in the tubing string at the desired position at either ofsuch seat inserts. Sin'riiar-lyfit will be seen that while the plug 19 must be introduced into the upper end of the tubing string with the sealing assembly 47 in a lower position, since the plug roots longitudinally symmetrical and is provided with a pair of snap'rings' which are spaced on opposite sides of the shoulders 131 of the external flange 132 of the sleeve of the plug 100, the plug 100 will latch in place at a seat insert l'l or 125 regardless of which of its ends is in lower position.

It willfnow be seen that both forms of the plug are secured to a seat insert at a desired location in a flow conductor, such as a well tubing, against longitudinal movement therein and that they have sealing means spaced on opposite sides of such seat insert to seal with the tubing to prevent flow of fluid in either direction through the tubing Slfiflg' 'It will further be seen that both plugs are of simple, economical construction and that the components thereof are easily assembled to form the plug.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, within the scope ofthe appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patenti'sr' 1. A well tool for closing the flow passage of a well flow conductor having a pair of longitudinally spaced oppositely lacing shoulders, said well tool including: a mandrel, 'seal means on opposite ends of said mandrel for sealingly engaging internal surfaces of said well flow conductor; stop means on said mandrel engageable with one of said shoulders of said flow conductor for limiting movement of said well tool in the flow conductor in one direction and latch means carried by said mandrel and engageable with the other of said shoulders of said flow cona doctor for preventing movement of said well tool in the shoulder 120 of whichever snap ring 116 is in lower" position on the sleeve 110 engages the upper stopshou l der 130 of the seat insert and is first carnmed thereby into its recess 114 of the sleeve 110 and then expands outwardly when the plug moves downwardly a sufiicient dis tance in the stop or seat insert to cause the snap lock ring to be positioned below the upper lock shoulder 135 inftlgej locking recess 133 of the seat insert. At this time which. ever shoulder 122 of the flange 121 of the sleeve faces downwardly then engages the upwardly facing stop shoulder 130 of the stop or seat insert to arr est further downward movement of the plug in the tubing, The ,flange oi the sleeve which engages the upper stop shoulder 130 opposite direction in the flow conductor, said stop means said latch means being disposed between said seal means.

' 2. A well tool for use in a flow conductor having a flow a passage; a seat insert having an upwardly facing inwardly of the insert and the snap ring which. is in 7 tion in the latch recess 133 of the seat ring'd sQdjtQ engage the upper stop shoulder 135 of recess in the seat insert then prevent movement of the plug longitudinally of the tubing with respect to the stop or seat insert ifi'ld downwardly beveled upper shoulder extending into the flow passage of the flow conductor and also having an abrupt downwardly fscin'g'shoulder' spaced below said upwardly facing shoulder and an integral external annular flange thereon adapted to be positioned between adjacent sections of said flow conductor at a coupling reeessthereima plug including a mandrel having external stop means for engaging said upwardly facing shoulder to limit downward movement of said plug in said flow conductor, resilient contractible and expansible latch means carried by said mandrel and normally proiecting laterally therefrom so as to be engageable with said downwardlyfacing shoulder for limiting upwrad movement of the plug in the flow'conductor, and a seal means carried by sand mandrel for engaging said flow conductor at a point spaced longitudinally of said conductor from said insert to prevent flow of fluids through the flow passage of the flow conductor in either direction.

3. A well plug including: an elongate mandrel having ,ex ternal stop means thereon providing longitudinally spaced oppositely facing stop shoulders; expansible latch means carried by said mandrel and disposed on opposite side-s of said stop means; and a pair of seal means carried by said mandrel adjacent opposite ends thereof and disposed longitudinally outwardly of said latch means.

4. A well tool including: seat insert means connectible in a well flow conductor and providing longitudinally spaced oppositely facing seat and lock shoulders; a plug member insertable through said Well conductor and having means thereon providing a stop shoulder engageable with the seat shoulder of said seat insert means, resilient compressible and expansible latch means on said plug member inherently biased outwardly of said plug member to a projecting position engageable with said lock shoulder of said seat insert means, and seal means on said plug member engageable with said flow conductor to prevent flow of fluids through the conductor in either direction when said plug member is engaged with the said stop and lock shoulders of said seat insert means.

5. A well tool for closing the flow passage of a well flow conductor and comprising: insert means connectible in said well flow conductor and providing a projecting seat shoulder and a longitudinally spaced oppositely facing lock shoulder projecting into the bore of said flow conductor; and a plug assembly comprising a mandrel, stop means on said mandrel engageable with said seat shoulder for limiting movement of said plug assembly in said flow conductor in one direction, resilient contractible and expansible latch means on said mandrel normally inherently biased to a projecting position engageable with said lock shoulder for preventing movement of said plug assembly in the opposite direction in said flow conductor, and a pair of seal means on said mandrel adjacent the opposite ends thereof for sealingly engaging the internal surfaces of said well flow conductor on opposite sides of said insert means to shut off flow of fluids through the flow passage of the conductor.

6. A well tool for use in a string of connected sections of well flow conductor, said tool including: a seat and lock insert member adapted to be connected in said well flow conductor, said member having an integral external annular flange disposed to be confined between adjacent sections of said well flow conductor, whereby said member is positively positioned in said well flow conductor against movement in either direction therein and having a seat shoulder and an oppositely facing lock shoulder; a plug assembly insertable in said well flow conductor and comprising a mandrel, stop means on said mandrel engageable with the seat shoulder of said insert member for preventing movement of said plug assembly in one direction past said insert member, resilient substantially annular contractible and expansible latch means mounted on said mandrel and resiliently movable outwardly thereof into position to engage said lock shoulder of said insert member to prevent movement of said plug assembly in the opposite direction with respect to said insert member; and a pair of longitudinally spaced seal means carried by said mandrel engageable with the flow conductor on opposite sides of said insert member to prevent flow of fluids past said plug assembly.

7. A well tool including: an annular lock and seat insert member having means for mounting it in a well flow conductor and having oppositely facing longitudinally spaced seat shoulders thereon and a pair of oppositely facing internal annular latech shoulders in its bore intermediate the oppositely facing seat shoulders; and a plug assembly comprising a mandrel; means pro-viding oppositely facing stop shoulders on said mandrel; a pair of. spaced latch means disposed on longitudinally opposite sides of said means providing said stop shoulders, said latch means each being resiliently biased outwardly of said mandrel to a projecting position, whereby one of said latch means engages with said lock shoulders of said inert member when one of said stop shoulders on said mandrel engages one of the seat shoulders of said insert member to latch said plug assembly to said insert member; and seal means carried by said mandrel and spaced longitudinally beyond each of said latch means and adapted to seal with a well flow conductor on opposite sides of said insert member to prevent fluid flow in either direction past said plug assembly.

8. A well tool including: an annular ring insert having an external annular flange thereon adapted to be engaged between the ends of adjacent sections of a well flow conductor, whereby said insert is held in place in said well flow conductor against longitudinal movement therein, means on said insert ring providing a seat shoulder projecting into the bore of said well flow conductor and a stop shoulder spaced longitudinally from and facing in the opposite direction to said seat shoulder; and a plug assembly comprising a mandrel; external annular flange means on said mandrel engageable with said seat shoulder of said ring insert to limit movement of said plug assembly in one direction in a well conductor with respect to said ring insert; latch ring means on said mandrel and resiliently biased outwardly thereof to a position projecting from said mandrel disposed to engage said stop shoulder of said ring insert to limit movement of said plug assembly longitudinally in the opposite direction with respect to said ring insert; and a pair of longitudinally spaced bulbous seal members carried on opposite ends of said mandrel assembly and disposed to engage said well flow conductor to prevent flow of fluids therepast in either direction, said seal members engaging said well flow conductor on opposite sides of said ring insert when said plug assembly is in engagement with said ring insert.

9. A well tool including: an annular seat and lock insert ring member adapted to be positioned in a well flow conductor, said ring member having an external annular flange thereon adapted to be disposed between the adjacent ends of adjacent sections of a well flow conductor and confined therebetween, whereby said seat and lock ring insert is held against longitudinal movement in said well flow conductor, said insert ring having opposed longitudinally spaced annular seat shoulders thereon projecting into said well flow conductor, said insert ring also having a recess formed in its bore intermediate the seat shoulders thereof and providing a pair of longitudinally spaced oppositely facing lock shoulders in said bore of said conductor of said insert ring; and a plug assembly comprising a mandrel, external flange means on said mandrel providing a pair of oppositely facing stop shoulders disposed in the central portion of said mandrel and adapted to engage one of said seat shoulders of said insert ring to limit movement of said plug assembly longitudinally through said insert ring, a pair of longitudinally spaced latch ring means disposed on said mandrel on longitudinally opposite sides of said external annular flange means and resiliently biased outwardly of said mandrel, each of said latch ring means being adapted for engagement in the recess in said insert ring for locking engagement with one of the lock shoulders in said recess to prevent longitudinal movement of said mandrel in the opposite direction with respect to said insert ring when the adjacent stop shoulder is engaged with one of said seat shoulders, and a pair of bulbous seal members on the opposite ends of said mandrel and disposed to engage in sealing relation the well flow conductor to seal oil flow of fluids therepast, said seal members being disposed on opposite sides of said insert ring when said plug assembly is in seating and latching engagement with said insert ring.

10. A seat insert for a well flow conductor having longitudinally aligned sections connected in spaced relationship to one another by a connecting means, said seat insert including: an annular member having an outwardly integral external annular flange portion receivable between adiacent ends of adjacent sections of a well flow conductor whereby said seat insert may be secured to said well flow conductor against longitudinal movement relative thereto, said annular member having an inner portion extending inwardly of said tubing sections providing oppositely facing stop and latch shoulders, said stop shoulder being beveled inwardly and longitudinaily toward said latch shoulder and said latch shoulder extending substantially normal to the longitudinal axis of the bore of said annular member, said stop and latch shoulders of said annular member being engageable with stop and latch means respectively of a plug for limiting longitudinal movement of the plug relative to the seat insert.

11. A seat insert for a well flow conductor having longitudinally aligned sections. connected in spaced relationship to one another by a connecting means, said seat insert including: an annular member having an outwardly extending integral external annular flange portion receivable between adjacent ends of adjacent sections of a well flow conductor whereby said seat insert may be secured to said well flow conductor against longitudinal movemenfreiafive thereto, said annular member having an annnlaruportion extending inwardly of said tubing sections ,liaving inwardly convergent oppositely facing stop shoulders at opposite ends thereof, said annular portion having an internal annular recess defined by longitudinally spaced parallel annular lock shoulders extending at a right angle to the longitudinal axis of the bore of said annular member.

References Cited in the tile of this patent UNITED STATES PATENTS 2,394,977 Boynton Feb. 19, 1946 2,436,525 ODonnell Feb. 24, 1948 2,506,680 Otis May 9, 1950 

1. A WELL TOOL FOR CLOSING THE FLOW PASSAGE OF A WELL FLOW CONDUCTOR HAVING A PAIR OF LONGITUDINALLY SPACED OPPOSITELY FACING SHOULDERS, SAID WELL TOOL INCLUDING: A MANDREL, SEAL MEANS ON OPPOSITE ENDS OF SAID MANDREL FOR SEALINGLY ENGAGING INTERNAL SURFACES OF SAID WELL FLOW CONDUCTOR; STOP MEANS ON SAID MANDREL ENGAGEABLE WITH ONE OF SAID SHOULDERS OF SAID FLOW CONDUCTOR FOR LIMITING MOVEMENT OF SAID WELL TOOL IN THE FLOW CONDUCTOR IN ONE DIRETION AND LATCH MEANS CARRIED BY SAID MANDREL AND ENGAGEABLE WITH THE OTHER OF SAID SHOULDERS OF SAID FLOW CONDUCTOR FOR PREVENTING MOVEMENT OF SAID WELL TOOL IN THE OPPOSITE DIRECTION IN THE FLOW CONDUCTOR, SAID STOP MEANS AND SAID LATCH MEANS BEING DISPOSED BETWEEN SAID SEAL MEANS. 